One of the major questions being pursued in developmental biology today is "How are specific genes turned on and off at the appropriate times in a developmental sequence?" The ultimate goal of the research conducted in our laboratory is to study the modes of regulation involved in differentiation in the life cycle of the dimorphic bacterium Caulobacter crescentus. The work contained in this proposal will involve a sequence analysis of the promoter regions for a variety of C. crescentus genes. The comparison of promoter sequences of genes expressed throughout the cell cycle to those which have cell cycle-dependent expression should provide us with some insight into the mechanisms involved in temporal regulation of gene expression. In addition, we will study gene regulation in C. crescentus in response to changes in the external environment. These studies will demonstrate some of the mechanisms used for the regulation of gene expression by this organism, and will give us greater insight into the physiology of C. crescentus. Furthermore, they should provide us with a better ability to study the regulation of cell cycle events. Specifically we propose: (1) to determine the nucleotide sequence of the promoter regions of several flagellar genes, (2) to determine the nucleotide sequence of several biosynthetic gene promoter regions, (3) to study the regulation of stalk length in response to phosphate limitation and the presence of exogenous phosphorylated compounds, (4) to study the regulation of the genes involved in the catabolism of histidine, (5) to study the regulation of the genes involved in the catabolism of lactose, (6) to look for the presence of transposable elements in the C. crescentus genome, (7) to devise a method for the transformation of C. crescentus with plasmid DNA, (8) to provide genetic expertise and strains for other laboratories study C. crescentus as well as for laboratories seeking to adapt genetic techniques developed for C. crescentus to studies with other gram-negative bacteria.